A turbine exhaust case of an aircraft gas turbine engine is typically used to form a turbine exhaust, duct for aerodynamic fairing. A tail cone is attached to the aft end of the turbine exhaust case. Radially outwardly extending flange connections which are used for case connections of the engine casing at other locations, are not suitable for the attachment of the tail cone to the exhaust case because the radially outwardly extending flanges would interfere with the aerodynamic fairings of the turbine exhaust duct. Conventionally, a turbine exhaust case is configured with the aft end thereof including an annular axially extending flange to be inserted into the front opening of the tail cone and the two components (the exhaust case and the tail cone) are secured together by fasteners, for example, as shown in FIGS. 6A and 6B. However, the axially extending annular flange, in contrast to the radially outwardly extending annular flanges, adds no additional stiffening reinforcement to the large diametrical open aft end of the turbine exhaust case. In order to stiffen the aft end of the turbine exhaust case, particularly when the turbine exhaust case is made of sheet metal, a ring of thick sheet metal is conventionally attached to the inner surface of the axially extending annular flange of the turbine exhaust case, as more clearly shown in FIG. 6B and indicated by letter A. However, the ring of thick sheet metal added to the aft end of the turbine exhaust case has only limited stiffening function and also adds undesirable weight thereto.
Accordingly, there is a need to provide an improved structural arrangement for annular exhaust duct and tail cone attachment.